JP2000078881A - Brushless motor and rotation signal detecting circuit thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a brushless motor capable of calculating the accurate number of revolution, irrespective of low number of revolution and high number of revolution, by eliminating noise from a Hall element for rotation detection. SOLUTION: This detecting circuit is provided with a first filter 25 which receives a rotation signal Aa of a Hall element 4a for rotation detection and passes a low frequency rotation signal Aa2 at the time of low rotation, and a second filter which receives the rotation signal Aa and passes a high frequency rotation signal Aa2 at the time of high rotation. An output end of the first filter 25 is connected with an input port 30a for the rotation signal of a microcomputer 29. An output end of the second filter 26 is connected with an input port 30b of the microcomputer 29. On the basis of the states of the input ports, the microcomputer 29 reads the data written in either input port and calculates the number of rotations of the motor main body part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly, to a brushless motor capable of calculating an accurate rotation speed irrespective of low rotation and high rotation.

[0002]

2. Description of the Related Art A motor for rotating a blower fan in an automobile air conditioner is a brushless motor in which a permanent magnet is used as a rotor, an armature winding is used as a stator, and a rectifying mechanism is replaced with a magnetic pole sensor and a switching element. It is becoming possible.

A description will be given with reference to a configuration diagram of this conventional brushless motor. FIG. 10 is a schematic configuration diagram of a brushless motor. FIG. 10 is a configuration diagram of a motor body of the brushless motor.

[0004] As shown in FIG.
Are a motor circuit 2, a drive circuit 3 for supplying drive signals of different phases to each coil of the motor body 2 by a plurality of switching elements, and a Hall element 4 a for detecting rotation of the motor body 2. A filter 5 for removing noise from the detection signal (hereinafter referred to as a rotation signal).

The filter 5 has a filter characteristic of filtering a rotation signal at the time of low rotation by narrowing the frequency band or a filter characteristic of filtering a rotation signal at the time of high rotation by expanding the frequency range to a high frequency band.

A rotation signal from the filter 5 is received by one input port 6a, and a control signal to the drive circuit unit 3 is transmitted from the rotation signal of the input port 6a and a target rotation speed from an operation unit (not shown). A microcomputer 6 is provided.

[0007] The microcomputer 6 controls the rotation signals (Hall element 4a) from the Hall elements 4a, 4b and 4c of the motor body 2.
Is input through a filter 5), the position of the magnetic pole of the sensor magnet is determined from these rotation signals, and the drive circuit unit 3 is determined from the determined position, the rotation speed of the rotor and the target rotation speed. Of the plurality of transistors is determined. This target rotation speed is a rotation speed obtained based on a FAN command voltage from an amplifier (not shown).

Further, the number of rotations of the rotor (the rotor and the FAN are connected) is determined based on the number of pulses of the rotation signal from the Hall element 4a.

As shown in FIG. 11, the motor body 2 has a magnet 8 (hereinafter referred to as a sensor magnet 8) for detecting rotation around a shaft 7, and six magnets around the sensor magnet 8. A stator 9 having salient poles 9a, 9b,... Is attached.

Further, the six salient poles 9a, 9b,
A coil is wound around. Further, magnets 11a, 11b,... For generating rotation at predetermined intervals are provided on the inner periphery of the rotor 10 covering them.

Further, the hall elements 4a, 4b and 4c are attached to the stator 9 at intervals of 120 degrees.

In the conventional brushless motor configured as described above, the filter 5 receives the rotation signal of the Hall element 4a, removes noise contained in the rotation signal, and removes the noise from the microcomputer 6.
To send to. That is, the noise generated from each coil of the stator 9 or the external noise
This noise is removed even if detected by a.

The microcomputer 6 receives the rotation signal from the filter 5 at an input port 6a, and determines the rotation signal from the falling edge (or rising edge) of the rotation signal to this port and the previous falling edge (or rising edge). The rotation speed is obtained by measuring the time between both edges.

The microcomputer 6 is provided with each of the Hall elements 4a, 4a
b, 4c, the position of the magnetic pole (N, S) of the sensor magnet 8 is determined, and based on this position and the rotation signals from the Hall elements 4a, 4b, 4c, the switching elements of each switching element are determined. A control signal for controlling on / off switching timing is generated. In generating the control signal, the difference between the rotation speed obtained based on the rotation signal of the Hall element 4a and the target rotation speed, and the magnetic pole position are used.

Then, the drive circuit unit 3 generates six field effect transistors (MOSs) (not shown) based on the control signal.
By driving the FETs sequentially, the blower fan connected to the rotor 10 is rotated to send air from the outlet.

[0016]

However, in the conventional brushless motor, the rotation signal of the Hall element 4a is input to one input port of the microcomputer after removing the noise by one filter and input to this input port. The rotation speed of the rotor is determined from the time difference between the falling edge (or rising edge) of the rotation signal and the falling edge (or rising edge) of the previous rotation signal.

However, the rotation speed of the rotor of the brushless motor is controlled to a high-speed rotation or a low-speed rotation depending on the external temperature, the state of the outside air, and the like.

However, the conventional brushless motor has either a filter characteristic of filtering a rotation signal at a low rotation speed by narrowing a frequency band or a filter characteristic of filtering a rotation signal at a high rotation speed by expanding to a high frequency band. The noise of the rotation signal of the Hall element 4a is removed by a single filter.

For this reason, for example, when trying to pass a rotation signal at the time of low-speed rotation by narrowing the frequency band, there is a problem that even the noise can be removed, but even the rotation signal at the time of high-speed rotation is removed.

Conversely, if a filter is used to expand the frequency band and pass the rotation signal at the time of high-speed rotation, noise generated following the rotation at low-speed rotation cannot be removed. There were challenges.

Furthermore, the conventional brushless motor uses the time difference between the falling edge (or rising edge) of the rotation signal input to one input port and the falling edge (or rising edge) of the previous rotation signal to determine the rotor position. The number of rotations is determined.

Therefore, if the output from one filter as described above is input to one input port, a single filter having a narrow frequency band outputs a rotation signal for rotation detection at high speed rotation to the input port. Therefore, there is a problem that the microcomputer stops the control signal to the drive circuit unit and stops the air blow.

On the other hand, in the case of a filter whose frequency band is expanded, noise is not removed at the time of low-speed rotation and is input to the input port, so that there is a problem that the microcomputer sends an erroneous control signal to the drive circuit.

The present invention has been made to solve the above-mentioned problems, and it is possible to remove the noise from the Hall element for detecting rotation to calculate an accurate rotation speed irrespective of low rotation and high rotation. An object is to obtain a brushless motor.

[0025]

A rotation signal detecting circuit for a brushless motor according to the present invention comprises a permanent magnet as a rotor, an armature winding as a stator, and a plurality of Hall elements arranged at regular intervals on the stator. In a rotation signal detecting circuit for inputting an output from any one of the Hall elements as a rotation signal, a first filter passes a frequency band of a rotation signal transmitted from the Hall element when the rotor rotates at a low speed. A detection signal at the time of low rotation obtained by filtering the rotation signal having frequency characteristics is transmitted.

Further, the second filter receives a rotation signal having a second frequency characteristic to pass up to the frequency band of the rotation signal transmitted from the Hall element at the time of high rotation, and is filtered by the second frequency characteristic. Outputs rotation signal at high rotation.

Further, in the brushless motor of the present invention, a permanent magnet is used as a rotor, an armature winding is used as a stator, and a plurality of Hall elements are arranged on the stator at regular intervals. Is a rotation signal, a brushless motor that supplies a multi-phase drive signal to the armature winding to make the rotor low or high rotation from the rotation speed and the target rotation speed obtained based on the rotation signal, A first filter having a first frequency characteristic to pass a frequency band up to a rotation signal transmitted from the Hall element at the time of low rotation, and inputting a rotation signal from the Hall element and filtering the first frequency characteristic; A rotation signal at the time of rotation is transmitted.

The second filter has a second frequency characteristic in a frequency band through which the second filter passes up to a rotation signal transmitted from the Hall element when the rotation is high, and inputs the rotation signal.
A rotation signal at the time of high rotation filtered by the second frequency characteristic is output.

The control operation unit sets one of the two input ports as a low-rotation input port for inputting a low-speed rotation signal and inputs the other input port with a high-speed rotation signal. Low and high rotation input ports
When a high rotation signal is input and both input ports are in the same logical state, the number of rotations is obtained from the data of the input port for low rotation,
When the logic states of the input ports are different, the rotation speed is obtained from the data of the input port for high rotation.

In the brushless motor of the present invention, a rotation signal from one of the Hall elements provided on the stator is
The first filter and the second filter are input, and the first filter sends a rotation signal sent from the Hall element when the rotation is low, and the second filter sends a rotation signal sent from the Hall element when the rotation is high. Send out.

The control operation unit inputs the rotation signal from the first filter to the low rotation input port and the rotation signal from the second filter to the high rotation input port. From the state, either the data of the input port for low rotation or the data of the input port for high rotation is adopted to determine the rotation speed.

Therefore, when the rotor is rotated at a low speed, the first filter removes noise superimposed on the rotation signal at the time of the low rotation due to the rotation of the rotor, and the low speed rotation of the control operation unit is performed. The rotation signal and noise at the time of low rotation are sent out from the second filter as they are, and are input to the input port for high rotation of the control operation unit.

When the rotor is rotated at a high speed, noise superimposed on the rotation signal at the time of the high speed rotation is removed by the second filter by the second filter. Input to the input port. At this time, the rotation signal is not transmitted from the first filter.

Then, the logic states of the input port for high rotation and the input port for low rotation are read by the control operation unit, and when the logical states of both input ports are different, the input port of high rotation is input. The rotation speed is obtained from the data, and when both input ports are in the same state, the rotation speed is obtained from the data of the input port for low rotation.

In other words, when a logical state occurs in which a rotation signal is present from the first filter and a rotation signal is present from the second filter, noise associated with low rotation that cannot be removed by the first filter passes through the second filter. Therefore, the rotation speed based on the data of the low rotation input port to which the rotation signal from the first filter is written as the low rotation time is obtained.

When there is no data in both input ports, the rotation is stopped, and the control is performed to read the input port for low rotation.

Further, when there is no data at the low rotation input port and there is data at the high rotation input port, the detection signal and noise of the Hall element are removed by the first filter at the time of high rotation. Therefore, the rotation speed is obtained based on the detection signal of the input port for high rotation.

[0038]

As described above, the rotation signal detecting circuit of the brushless motor of the present invention inputs the rotation signal from the rotation detecting Hall element provided on the stator to the first filter and the second filter. The first filter sends out the rotation signal at the time of low rotation in the frequency band up to the rotation signal sent from the Hall element at the time of low rotation, and the second filter sends the rotation signal sent from the Hall element at the time of high rotation. The rotation signal at the time of high rotation in the frequency band of is transmitted.

Therefore, it is possible to transmit a rotation signal corresponding to the time of low speed rotation or high speed rotation to the subsequent stage, and to input the respective rotation signals from the first filter and the second filter in another system in the subsequent stage. Has been obtained.

According to the brushless motor of the present invention, the rotation signal from the hall element for rotation detection is filtered through the first and second filters having different frequency characteristics from each other. The control operation unit inputs the signal to the input port for low rotation and the rotation signal at the time of high rotation to the input port for high rotation. If the states of both ports are different, the rotation speed is obtained from the data of the input port for low rotation.

For this reason, when there is a rotation signal from the first filter and a rotation signal from the second filter, noise due to low rotation that cannot be removed by the first filter passes through the second filter. Therefore, the rotation speed based on the data of the low rotation input port to which the rotation signal from the first filter is written as the low rotation time is obtained.

When there is no data in both input ports, the rotation is stopped, and the input port for low rotation is read.

Further, when there is no data in the input port for low rotation and there is data in the input port for high rotation, the detection signal and noise of the Hall element are removed by the first filter at high rotation. Therefore, the rotation speed is obtained based on the detection signal of the input port for high rotation.

Therefore, even if the rotor of the brushless motor is rotated at a low speed or a high speed, noise superimposed on the detection signal at each rotation is not erroneously read as a detection signal, so that an accurate rotation speed is always obtained. The effect that can be obtained.

[0045]

FIG. 1 is a schematic diagram of a brushless motor according to the present invention. Brushless motor 20 shown in FIG.
Receives a rotation signal Aa (a rotation signal Aa1 at the time of low rotation, a rotation signal Aa2 at the time of high rotation) of the rotation detecting Hall element 4a and passes a rotation signal Aa2 of a low frequency at the time of low rotation. An output terminal of the first filter 25, comprising: a filter 25; and a second filter 26 which receives a rotation signal Aa of the Hall element 4a for rotation detection and passes the rotation signal Aa2 having a high frequency during high rotation. Is connected to the rotation signal input port 30b of the microcomputer described later, and the output end of the second filter 26 is connected to the rotation signal input port 30a of the microcomputer described later. The rotation signal Aa written to the rotation signal input port is read to calculate the number of rotations of the motor body 2.

That is, the rotation signal Aa of the Hall element 4a for rotation detection is transmitted to the first filter 25 and the second filter 2
6, the rotation signals at the time of low and high rotations are extracted, the rotation signals from the respective filters are input to different input ports, and the low-speed or high-speed rotation is determined based on the logical state of both input ports. By reading the rotation signal of one of the input ports according to the determination result, noise at the time of low-speed or high-speed rotation is prevented from being read.

The rotation signal Aa of the Hall element 4 a provided on the stator 9 of the motor body 2 is
The rotation signal Aa is input via a buffer 23 to a second filter 26 for high rotation via a buffer 23.

Further, the rotation signal Ab of the Hall element 4b is supplied to the input port 30c of the microcomputer via the buffer 24 and the filter 28 (for noise removal), and the rotation signal Ac of the Hall element 4c is supplied to the buffer 21 and the filter 27 (for noise removal). ) Are input to the input port 30d of the microcomputer.

The first filter 25 is an RC filter comprising a resistor R1 and a capacitor C1, and has a frequency characteristic of passing a low-speed rotation signal Aa1 up to about 500 rpm, for example, as shown in FIG. ing.

That is, the rotation signal at the time of low rotation (for example, a frequency corresponding to 500 rotations or less) is passed.

The second filter 26 is an RC filter composed of a resistor R2 and a capacitor C2. For example, as shown in FIG. 3, the second filter 26 has a frequency characteristic of passing a rotation signal Aa2 having a frequency up to about 3000 rotations. ing.

That is, the rotation signal at the time of low rotation (for example, 3000 rotations or less) is passed.

On the other hand, as shown in FIG. 1, the microcomputer 29 has a plurality of input ports 30a, 30b, 30c, 30c.
, the input ports 30a and 30b are ports for detecting rotation, the input port 30a receives the rotation signal Aa from the second filter 26 for high rotation, and the input port 30b receives the first rotation signal Aa for low rotation. The rotation signal Aa1 from the filter 25 is taken in. .

The microcomputer 29 includes a rotation port signal presence / absence determining means 31 and a rotation port selection instructing means 3.
2, a rotation speed calculation means 33, and a control signal generation unit 34.

The rotation port signal presence / absence judging means 31 monitors the state of the input port 30a (also referred to as a high rotation port) and the input port 30b (also referred to as a low rotation port). It is determined whether Aa has been written, whether the rotation signal Aa1 during low rotation has been written to the input port 30b, or whether a signal has been written to both ports.
Then, the result of this determination is sent to the port selection instruction means 32 for rotation.

The rotation port selection instructing means 32 reads the result of the judgment by the rotation port signal presence / absence judging means 31, and based on the judgment result, the input port 30a or 30b.
One of the signals b is read, and the number of rotations is obtained from this signal.

The control signal generator 34 is provided for each of the Hall elements 4
b, 4c, the position of the magnetic pole (N, S) of the sensor magnet 8 is determined, and based on this position and the rotation signals from the Hall elements 4a, 4b, 4c, the switching elements of each switching element are determined. A control signal for controlling the on / off switching timing is generated and sent to the drive circuit unit 3.

The operation of the brushless motor configured as described above will be described below. For example, as shown in FIG. 4A, it is assumed that the rotation signal Aa1 at the time of low rotation is transmitted from the Hall element 4a, and that the rotation signal Aa1 has noise.

The rotation signal Aa1 is input to the first filter 25 and the second filter 26 via the buffers 22 and 23.

However, as shown in FIG. 2, the first filter 25 outputs a low-speed rotation signal Aa1 of up to about 500 rotations.
(8.3 Hz at 500 rpm), so that high-frequency noise components are removed, and only the low-speed rotation signal Aa1 is supplied to the input port 30a of the microcomputer 29 as shown in FIG. input.

As shown in FIG. 3, the second filter 26 allows the rotation signal Aa2 at the time of high rotation to pass by passing a frequency band of about 3000 rotations.

Therefore, as shown in FIG. 5A, for example, when the rotation signal Aa1 at the time of low rotation contains noise and is input to the second filter 26, as shown in FIG. This rotation signal Aa1 is directly input to the input port 30b. Of course, if the noise has a frequency corresponding to 3500 revolutions or more, the noise is removed by the second filter 26.

On the other hand, the rotor 10 of the motor body 2 is rotated at a high speed, and a high-speed rotation signal Aa2 shown in FIG.
Is transmitted from the Hall element 4a, the first filter 2
2, as shown in FIG. 2, since the low-speed rotation signal Aa1 has a characteristic to pass through, the high-frequency noise component and the high-speed rotation signal Aa2 are removed.

Since the second filter 26 has a frequency band of about 3000 rotations as shown in FIG. 3, the rotation signal A at the time of high rotation as shown in FIG.
When high frequency noise is included in a2 and input to the second filter 26, as shown in FIG. 7 (b), the noise is removed and the rotation signal Aa2 alone is input to the input port 30b. Of course, if the noise has a frequency corresponding to, for example, 3000 rotations or less, it is not removed.

The explanation for the above-mentioned noise will be supplemented. Generally, a brushless motor is driven by a three-phase drive signal, and is rotated at a low speed or a high speed by a FAN command voltage (not shown). That is, noise having a frequency following the low-speed or high-speed rotation is generated.

For example, in a high-speed rotation of 3000 rpm (period: 20 msec), noise corresponding to a frequency higher than 50 Hz, for example, 60 Hz or more, 500 rpm
At a low speed rotation of less than m rotations, for example, noise of 10 Hz or more is generated. The number of erroneous detections due to such noise is higher than that of external noise.

For this reason, as described above, the microcomputer 29 inputs the rotation signal of the first filter 25 to the input port 30a and the rotation signal of the second filter 26 to the input port 30b to determine whether the rotation port signal is present. The following operations are performed by the determination unit 31, the rotation port selection instruction unit 32, and the rotation speed calculation unit 33.

FIG. 8 is a flowchart for explaining the operation of the microcomputer 29 of the present embodiment. The rotation port signal presence / absence determination means 31 includes an input port 30a (high rotation port).
Then, the state of the input port 30b (low rotation port) is read (S1).

The rotation signal Aa is input to the input port 30b.
Is determined (S2). FIG.
In, the rotation signal written to the input port 30a is called a high rotation port signal.

In step S2, the input port 30b
If it is determined that there is a rotation signal Aa (high rotation port signal), it is determined whether the rotation signal Aa1 is written to the input port 30a (S3). In FIG. 8, the rotation signal Aa written to the input port 30a
2 is called a low rotation port signal.

In step S3, the input port 30a
When it is determined that the rotation signal Aa2 (low-speed port signal) is not written in the first port, the rotation port selection instructing means 32 performs a first noise determination process. That is, when the high rotation port signal is present at the input port 30a and the low rotation port signal is not present at the input port 30b, the first noise determination processing is performed.

That is, the input port 30b is connected to the second filter 26, and the second filter 26 removes the rotation signal Aa2 at the time of low rotation (for example, frequency noise 41.6 Hz corresponding to about 2500 rotations or less). Rotation signal Aa1 (for example, 3
(Frequency noise corresponding to 200 rotations or more has been removed) is written into the input port 30a.
Is performed.

By the processing of steps S2 and S3, the rotation port signal presence / absence determination means 31 sends a first determination result signal (low no high presence signal) indicating that there is no low rotation port signal and there is a high rotation port signal. Then, the rotation port selection instructing means 32 activates the counter 35 to count the first determination result signal (S4).

Next, the rotation port selection instructing means 32
Determines whether the count value Ki has reached "3" (S5). That is, it is determined whether or not the high-speed port signal is continuously written to the input port 30a only three times.

If it is determined in step S5 that the count value Ki has not reached "3", the process returns to step S1 to determine the state of both ports.

In step S5, the count K
When it is determined that i has reached “3”, that is, when the low rotation port signal is completely absent and the high rotation port signal is repeated three times, the normal high rotation port signal (no rotation signal) having no noise at the input port 30a It is determined that Aa1) has been written (S6). For example, the rotation signal Aa1 shown in FIG. 7B has been written.

Next, the rotation port selection instructing means 32
Clears the counter 35 to zero (S7), and sends a selection signal for causing the rotation speed calculation means 33 to read the high rotation port (input port 30a) (S8).

Therefore, the rotation speed calculating means 33 calculates the rotation speed based on the rotation signal Aa2 at the time of high rotation in which no noise exists.

In step S2, when the rotation port signal presence / absence determination means 31 determines that there is no high rotation port signal, the second noise processing is performed. Step S
When the rotation port signal presence / absence determination means 31 sends out a second determination result signal (high no signal) indicating that there is no high rotation port signal in the process of 2, the rotation port selection instructing means 32 activates the counter 35 and Then, the second determination result signal is counted (S9). Next, the rotation port select instructing means 32 determines whether or not the count value Ki has reached "3" (S10). That is, input port 3
It is determined whether or not the high-speed port signal has not been continuously written three times only in 0a. That is,
It is determined whether the data is noise data or regular data.

If the count value Ki has not reached "3" in step S5, the process returns to step S1 to determine the state of the input port 30a, which is a high rotation port.

In step S10, when it is determined that the count Ki has reached "3", that is, when the high-speed port signal is absent three times in a row, noise or a normal high-speed It is determined that none of the port signals (rotation signal Aa1) has been written (S11). That is, the FAN is in the stopped state (the rotor is in the stopped state).

Then, the counter 35 is cleared to zero (S
12), a selection signal for causing the rotation speed calculation means 33 to read the low rotation port (input port 30b) is transmitted (S1).
3).

Therefore, the rotation speed calculating means 33 reads the signal of the input port 30b which is a low rotation port.

Further, when the rotation port signal presence / absence determination means 31 determines that the high rotation port signal and the low rotation signal are present in steps S2 and S3, a third determination result signal (high / low / no signal) is output. Is sent to the rotation port selection instructing means 32, and the rotation port selection instructing means 32 sends a signal to read the state of the input port 30b which is a low rotation port to the rotation speed calculating means 33 (S14).

For example, as shown in FIG. 4 and FIG.
The rotation signal Aa2 from which noise has been removed is input to the second filter 26, and the rotation signal Aa2 at the time of low rotation is input from the second filter 26. However, as shown in FIG.
The rotation signal Aa2 including noise is input from the filter 26 of FIG.

For this reason, a low rotation port is selected by the processing in steps S2, S3 and S14.

As described above, in the present embodiment, the microcomputer 29 switches the port to be read as shown in FIG.

When there is data in the high rotation port and data in the low rotation port, that is, when both ports have the same data, the port is switched to the low rotation port.

When there is data in the high rotation port and no data in the low rotation port, that is, when the data state of both ports is different, the port is switched to the high rotation port.

Further, when there is no data in the high rotation port and there is no data in the low rotation port, that is, when both ports have no data, the port is switched to the low rotation port.

Therefore, when there is a rotation signal from the first filter 25 and a rotation signal from the second filter, noise due to low rotation that cannot be removed by the first filter 25 is removed by the second filter. 26, the rotation speed based on the data of the low rotation input port to which the rotation signal from the first filter 25 is written as the low rotation time is obtained.

When there is no data in both input ports, the rotation is stopped, and the input port for low rotation is read.

Further, when there is no data at the low rotation input port and there is data at the high rotation input port, the detection signal and noise of the Hall element are removed by the first filter at the time of high rotation. Therefore, the rotation speed is obtained based on the detection signal of the input port for high rotation.

Therefore, even if the rotor of the brushless motor is rotated at a low speed or a high speed, noise superimposed on the detection signal at each rotation is not erroneously read as a detection signal, so that an accurate rotation speed is always obtained. It is possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a brushless motor according to an embodiment.

FIG. 2 is an explanatory diagram illustrating frequency characteristics of a first filter 25.

FIG. 3 is an explanatory diagram illustrating frequency characteristics of a second filter 26;

FIG. 4 is an explanatory diagram illustrating an operation of a first filter during low rotation.

FIG. 5 is an explanatory diagram illustrating an operation of a second filter during low rotation.

FIG. 6 is an explanatory diagram illustrating an operation of a first filter at the time of high rotation.

FIG. 7 is an explanatory diagram illustrating an operation of a second filter at the time of high rotation.

FIG. 8 is a flowchart illustrating an operation of the microcomputer according to the present embodiment.

FIG. 9 is an explanatory diagram illustrating switching of input ports according to the present embodiment.

FIG. 10 is a schematic configuration diagram of a conventional brushless motor.

FIG. 11 is an external view of a motor body of the brushless motor.

[Explanation of symbols]

 4a Hall element 25 First filter 26 Second filter 29 Microcomputer 31 Rotating port signal presence / absence determining means 32 Rotating port select instructing means 33 Rotating speed calculating means 34 Control signal generating unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsuyoshi Sekine 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Corporation F-term (reference) 5H019 BB01 DD01 5H560 BB04 BB08 BB12 DA02 DA19 EB01 GG04 JJ13 TT02 TT08 XA05

Claims (5)

[Claims] 1. A permanent magnet is a rotor (10), an armature winding (12) is a stator (9), and a plurality of Hall elements are arranged on the stator (9) at regular intervals. A rotation signal detection circuit that inputs an output from the Hall element (4a) as a rotation signal, wherein the rotation of the Hall element (4a) is reduced when the rotor (10) rotates at a low speed.
a) a first filter (2) having a first frequency characteristic to pass up to the frequency band of the rotation signal transmitted from a) and transmitting a low-speed detection signal obtained by filtering the rotation signal;
5) inputting the rotation signal having a second frequency characteristic that allows the rotation signal to be transmitted up to a frequency band of the rotation signal transmitted from the Hall element (4a) at the time of the high rotation; A rotation signal detection circuit for a brushless motor, comprising: a second filter (26) that outputs a filtered rotation signal at the time of high rotation. 2. A permanent magnet is a rotor (10), an armature winding (12) is a stator (9), and a plurality of Hall elements are arranged on the stator (9) at regular intervals. The output of the Hall element (4a) is used as a rotation signal, and a multi-phase drive signal for causing the rotor (10) to rotate at a low speed or a high speed from a rotation speed and a target rotation speed obtained based on the rotation signal In the brushless motor to be supplied to the armature winding (12), the Hall element (4a) having a first frequency characteristic of passing a frequency band up to the rotation signal transmitted from the Hall element during the low rotation. A) a first filter (25) that receives the rotation signal from (1) and transmits a rotation signal at low rotation filtered by the first frequency characteristic; and a rotation filter transmitted from the Hall element at high rotation. Pass through to the traffic light A second filter (26) for inputting the rotation signal having a second frequency characteristic of a frequency band and outputting a rotation signal at the time of high rotation filtered by the second frequency characteristic; One of the input ports (30a, 30b) is used as a low-rotation input port (30b) for inputting the low-speed rotation signal, and the other input port receives the high-speed rotation signal. Input port for high rotation (30
As a), the low and high rotation signals are input, and when the logic state of both input ports is the same, the rotation speed is obtained from the data of the low rotation input port (30b). A brushless motor having a control operation unit (29) for obtaining the rotation speed based on data of the high rotation input port (30a) when the state is different. 3. The control operation section (29) switches a read input port to the low-speed input port (30b) when data is present in both of the input ports (30a, 30b). When there is no data in the low rotation input port (30b) and there is data in the high rotation input port (30a), the input port is switched to the high rotation input port (30a). Port selection instructing means (32) for sending a read port switching instruction for switching to the low rotation input port (30b) when there is no data in both ports; reading from the port selection instructing means (32) The input port for low rotation based on a port switching instruction (30b)
Alternatively, there is provided a rotation speed calculating means (33) for reading the write timing of the input port for high rotation (30a) and obtaining the rotational speed of the rotor from the previous write timing and the present write timing. The brushless motor according to claim 2. 4. The port selection instructing means (32), wherein no data is present in the low rotation input port (30b),
When there is data in the high-speed input port (30a), the state of both ports is monitored again. As a result, when both input ports keep the same state a predetermined number of times, the rotor rotates at high speed. The brushless motor according to claim 3, wherein the input port (30a) for the high rotation is switched to the middle position. 5. The port selection instructing means (32), when there is no data at the high-speed input port (30a), monitors the logic state of the high-speed port again, and as a result, 5. The brushless motor according to claim 3, wherein when the two input ports maintain the same logical state a predetermined number of times, the rotor is switched to the low rotation input port (30b) as being in low rotation.